Microsoft has been found guilty of patent infringement and ordered to pay a Guatamalan inventor Carlos Armando Amado almost $9m in damages.

The US District Court of Central California court ruled that Microsoft had infringed on his intellectual property and ordered it to pay him $8.96m.

This figure relates to software sold between March 1997 and July 2003 - Judge David Carter may review this figure to include software sold since 2003, according to Reuters. Damages are far lower than the $500m claimed for because the jury rejected nine out of ten claims made by Amado.

Microsoft expressed disappointment at the verdict but welcomed the rejection of Amado's huge damages claim. The company said its engineers started work on the data transfer technology independently before Amado approached them.

In 1990 Carlos Armando Amado filed a patent for software which helped transfer data between Excel spreadsheets and Microsoft's Access database using a single spreadsheet. He said he tried to sell this technology to Microsoft in 1992 but they turned him down. According to Amado, Microsoft started including his software in their releases between 1995 and 2002.

Microsoft is facing patent claims over Longhorn, the next version of Windows, from networking company Alacritech. Its lawyers are also due in court with Forgent Networks which claims the software giant infringed its JPEG picture compression patent.